Air bleed system

[dr_anthony]

Inspected today air bleed system .

At ISA on ground - N1 - 21,7 N2 - 60,8 EGT - 500 FF - 0,46

At 55 C on ground -  N1 - 21,6 N2 - 60,7 EGT - 508 FF - 0,40

At -55 C on ground -  N1 - 21,8 N2 - 60,9 EGT - 488 FF - 0,49

Check in UNEE (850 ft ASL)

To compare with FCOM:

Approximate standard day, sea level, stabilized idle indications (new engine).
                          N1 RPM N2 RPM  EGT      Fuel Flow
CFM 56-3          21.5%     60.3%    475°C    720 PPH

Taxi speed on idle on different temp are changes rapidly (slow at high OAT and near TO trust on low).

Excellent!

High idle looks very constantly. In descent in ISA with no winds from FL 370 to 2500 it increases from 31,2 N 1 to 33,2 (N2 EGT and FF also increases).

Anti-ice.

FCOM: 

Wing Anti-Ice System Operation.

Placing the WING ANTI-ICE switch ON when on the ground, opens both control
valves if thrust on both engines is below the setting for takeoff warning
activation and the temperature inside both wing distribution ducts is less than
the thermal switch activation temperature.
Both valves close if either engine thrust is above the takeoff warning setting or
either temperature sensor senses a duct overtemperature. The valves
automatically open if thrust on both engines is reduced and both temperature
sensors are cool.
With the air / ground sensor in the ground mode and the WING ANTI-ICE switch
ON, the switch remains in the ON position regardless of control valve position.
The WING ANTI-ICE switch automatically trips OFF at lift-off when the air / ground
sensor goes to the air mode.

On IXEG 737 wing AI valves don't closes in case of engine thrust is above the takeoff warning setting. Light on ground always illuminate bright - valve closed (not modeled yet?).

And on IXEG 737 wing AI switch don't automatically trips OFF at lift-off when the air / ground
sensor goes to the air mode, light illuminates dim - valves open only in air  (not modeled yet?).

Also noticed, that EAI or WAI on or off have no effect to the high idle value.  I can assume that it only feature of NG's with its systems of approach high idle.

Noticed that Dual bleed light don't illuminate with APU shutdown - very cool!, becouse APU bleed air valve closes automatical on its shutdown regardless of switch position.

Noticed also, that ram door full open light illuminate only with flaps down. But accordingly with FCOM it also may illuminate on slow speeds of the plane, isn't it?

Whew! Lets go to fly else and else on that wonderful bird.

 

[Litjan]

Hi,

 

As far as I know and remember, the wing-anti-ice valve is always closed on the ground - it only opens in the GRD TST position, but only until the thermal switch triggers and closes it. This is the way it was on the Classics I flew and the way we modeled it - no plans to change that, even if there are other configurations for the Classic.

The Classic has no automatic increase of N1 during engine or wing-anti-ice bleed extraction. Bleed supply is always sufficient to provide anti-icing, even at idle.

The ram door operation is not described very well in the manuals - it is completely independent and can not be influenced by the pilots. It says "at slow speeds", but there is no speed specified, so we only modeled the "flaps not up" - as that pretty much covers the slow speeds as well.

Cheers, Jan

 

[dr_anthony]

Hi, Jan. 

Yes, this is correct and i  did not realize so many variations of 737 CL in different airlines. I guided only by official boeing FCOM 1998 of year.

Then i look your first video i think - WTF, why in this plane switches are up to on and down to off, WTF is this.   

This thing are bring in that plane individuality and do it so atmospheric. Cool! 

Edited July 12, 2016 by dr_anthony